The present invention refers generally to a device comprising a centrifugal separator for cleaning of gases from impurities in the form of solid and/or liquid particles, such as oil mist. More specifically, the invention refers to a device comprising a centrifugal separator such as disclosed in WO 2009/029022.
Centrifugal separators of this kind are configured for cleaning of gases, such as air, especially contaminated or heavily contaminated air. The invention may in particular concern air in industrial environments, for instance air immediately in the proximity of various kinds of machines. Furthermore, this kind of centrifugal separators may be used for cleaning of other gases. For instance exhaust gases from stationary or mobile combustion engines.
One problem in connection with such cleaning is that the impurities contained in the gas to be cleaned contain a large proportion of solid or liquid particles which are very small and/or which have a relatively low density. Such small particles are difficult to separate also by means of centrifugal separators. A further problem in connection with such cleaning is that the particulate impurities contained in the gas to be cleaned get caught to the rotating member, and especially to the separation discs which are provided on the rotating member for rendering the separation efficient. Impurities, which may consist of both liquid and particulate impurities, form a more or less solid coating on the rotating member. This coating deteriorates the separation and makes it difficult to transport the impurities out from the separation space. Especially dry, i.e. solid, particies have a tendency to get caught on these surfaces, and thus form a relatively solid coating on the surfaces of the rotating member and in the separation space.
WO 2009/029022 presents a solution to these problems. However, in many case pressurised water, such as tap water, is not always available as the liquid to be supplied for humidifying the particles of the gas to be cleaned. When using pressurised water it is also difficult to achieve very small liquid particles.
Furthermore, cutting liquids are frequently used to improve the cutting process in machine tools. The cutting liquids may contain water-based emulsions, i.e. water and an oil, or various kinds of oils. When cleaning machine tool gases, i.e. gases, normally basically air, from or around a machine tool which contain such water-based emulsions, water may evaporate from the emulsion, which means that the cutting liquid turns into a highly viscous liquid, which is very hard to separate and discharge from the centrifugal separator. There is a risk that the liquid will get caught on the internal surfaces in the centrifugal separator.
A centrifugal separator of another kind is disclosed in U.S. Pat. No. 900,062. The cup-shaped rotating member is provided in an inner space of the separator. The rotating member has no separation discs, but a number of beaters and blades. A nozzle producing a spray is arranged so that the spray meets the gas entering the inner space in the gas inlet.